Problem with Repeats and Alternatives

[John Helly]

    Aloha.
      
      I've not used LP for a while but in coming back to it I've been
      struggling with repeats and find that this 'preferred syntax' does
      not seem to work in that it produces:

Starting lilypond 2.20.0 [test2.ly]...

Processing `/Volumes/Pegasus32R6/Music-100/Music-Lilypond/Songs/Our-Shangri-La/test2.ly'

Parsing...

/Volumes/Pegasus32R6/Music-100/Music-Lilypond/Songs/Our-Shangri-La/test2.ly:6:10: error: syntax error, unexpected \alternative

      ...
      
      \version "2.20.0"
      {
      \fixed c'' {
             \repeat volta 6 {
               c4 d e f
               \alternative {
                 \volta 1,2,3 { c2 e }
                 \volta 4,5 { f2 d }
                 \volta 6 { e2 f }
      } }
      c1 }
      }
      
      However, the old style of specifying \alternative does seem to
      work. Am I doing something wrong here?
      
      Mahalo.
      J.-
John Helly, University of California, San Diego / San Diego Supercomputer Center / Scripps Institution of Oceanography / 760 840 8660 mobile / http://www.sdsc.edu/~hellyj
ORCID ID: orcid.org/0000-0002-3779-0603